Sustainable hand-retrievable wide-area supported catalysts for waste water remediation: Role of support features in mitigating the catalytic performance

Nanocatalysts are extremely crucial for the expedited synthesis of various chemicals, fuels, and pharmaceutical molecules both in academia and industry. To overcome the limitations of nanocatalysts and or microstructure supported catalysts such as agglomeration (due to inter-particle dipolar forces preventing longer shelf-lives), compromised catalytic activity (e.g., nickel-titanium dioxide bimetallic catalyst, showed high selectivity to hydrogenate 3-nitrostyrene into 3-vinylaniline (90.2 %) compared to unmodified nickel (55.3 %), due to metal-plane formation by titanium dioxide), cytotoxicity (with over 90 % cell killing in the presence of the nanocatalysts above ∼ 0.2 mg/mL), catalyst retrieval (demanding energy intensive procedures such as centrifugation (∼10,000 g and above), membrane filtrations (∼0.2 µm), magnetic separations (0.9–1.1 T) and absurd practical implementation there is a tremendous development of 3-dimensional wide-area supported catalysts. This review update the readers on the evolution of highly catalytic nanoparticles for various heterogeneous catalysis. Uniquely, wide-area supported catalysts wherein the nanoparticles are grafted to 3-dimensional nature-inspired or pristine natural materials as sustainable strategies are discussed. The role of wide-area of the support in overcoming the limitations of nanocatalysts and microstructures by enabling bidirectional reactant access, catalyst efficiency, reusability, stability and sustainability are highlighted. Next, we focus on the metal-affinity and redox-potential of the natural support that aid autogenic biosynthesis and self-assembly of nanocatalysts. Followed by discussions on supplementary properties of the support such as type, structural-hierarchy, surface-area, absorption, porosity and rigidity in tuning the stability, biodegradability, compatibility, functionality and performance of the catalyst. Accentuated, with the impact of support in dictating the choice of fixed batch vs continuous flow reactors, co-relative to modulating the catalytic efficiency and turnover frequencies. Finally, the exclusive role of wide-area of the support and its biological nature in allowing the extraction of noble precursor off the support after catalyst poisoning is emphasized. These discussions, for the first time, spotlight the versatility, resilient nature of the emerging ultra-efficient wide-area supported catalysts that are generated using sustainable procedures for diverse large-volume heterogeneous catalysis.